1. Field of Invention
This invention relates to device that provides a continuous flow of clean, breathable air to an enclosed space.
2. Background of the Invention
Terrorists have begun to threaten mass destruction. Their attacks include biological, chemical and radiological weapons. They seek to inflict maximum damage by detonating these weapons in highly populated areas. Because air can quickly spread these lethal payloads, people would become victims in their homes and work places. There is a need to protect individuals and groups from this threat.
The Office of Homeland Security suggested that families retreat to a designated room. This room would be sealed with Duct tape. The tape would prevent contaminated air from entering it. This defense was quickly discredited for two reasons. First, it was unlikely that the room could be totally sealed. There would be leakage points missed such as those illustrated in FIG. 1. Second, if the room was successfully sealed, the occupants would soon be without oxygen.
Another defense is to place an air purifier or air filter in the room. But these devices only clean the air after it has entered the room. The purifiers and filters will eventually clean the air, but not before the occupants are exposed. Also, if the air pressure within the room is lower than the air pressure outside the room, contaminated air would flow into the room. Air cleaners do not add air to the room. They do not prevent this inflow of contaminated air. Finally, purifiers and filters are not effective against a full range of contaminates. Mechanical and electronic filters are effective with particulate materials but have little or no effect on bacteria and chemicals. Gas phase filters are needed for chemicals. Still other mechanisms, such as ultra-violet light, are used in purifiers which target bacteria and viruses. There is no single system that rids the air of all contaminates.
Air conditioners are similar to air filters in that they simply recirculate existing air within a room. While many contain air filters, their primary function is to cool the air, not clean it. Therefore, air conditioners would be even less effective at protecting occupants from air-borne contaminates than air cleaners or air filters.
Another defense is to build a clean-room. Clean-rooms have been used in the medical, chemical and electronics industries. In the medical and chemical industries, clean-rooms are usually designed to prevent chemical fumes and biological agents from escaping the work space. In the electronics industry, the reverse is often true. There the clean-rooms are designed to prevent outside air from contaminating the enclosed work space.
These industrial clean-rooms achieve their objective by providing a hermetically sealed room. Attached to this room is an air flow system capable of moving air in and out of the room. The air flow system is designed to clean the air of any contaminates. By balancing the inflow and outflow of air, the air flow system maintains the room at a desired pressure level and cleanliness. Ludwig G. Rockx (U.S. Pat. No. 5,063,835, Nov. 12, 1991) described the construction of an industrial clean-room. Gordon P. Sharp, et. al. (U.S. Pat. No. 5,385,505, Jan. 31, 1995) describes a mechanism for controlling the air flows in and out of an industrial clean-room.
These industrial units are effective at maintaining a clean enclosed space. Unfortunately, they are not easily adapted to the residential or office work environment. Hermetically sealed spaces could be built in new private residences or offices, but they would be very costly. In existing units, it would be both costly and difficult.
Additionally, the cost of the ventilation system required to support these clean-rooms is high. Air flow systems like those described in U.S. Pat. No. 5,385,505 are expensive, usually dedicated to specific contaminates, and require highly skilled maintenance personnel. These systems are not easily or economically transferred from the industrial sector to home use.
Presently, there is no air cleaning system that can be economically and effectively installed in a residential or office space. The existing air cleaning systems suffer from one or more the following deficiencies and disadvantages:                a) They fail to prevent exterior air from seeping into the enclosed space or room.        b) They fail to compensate for pressure differentials between the enclosed space and the air outside the enclosed space.        c) They fail to provide the flexibility to respond to several different air-borne contaminates.        d) They fail to provide a means to safely maintain the system after use.        e) They fail to provide for a economical installation.        f) They are not portable.        g) They are not quickly and easily installed.        h) They require expertise to install, operate, and maintain.        